Abstract: One strain of imazethapyr-degradable bacterium named P14 was isolated from the sludge of imazethapyr production plant by high pressure enrichment method.Classification was determined by analysis of morphological,physiological and biochemical characters and sequencing of 16S rDNA for P14 strain.P14 strain was identified as Shewanella hafniensis.Degradation performance was investigated preliminary,in the mineral salt medium with imazethapyr as sole carbon source.The optimal parameters for P14 strain to degrade imazethapyr up to 92 % within 3 d were at 30 ℃,pH 6.0,inoculated by 7%,and at 100 mg/L imazethapyr.After other carbon source added,the degradation ratio of P14 to imazethapyr was decreased.It's found that sodium citrate was not likely to affect the degradation ratio compared with other carbon sources.